1. Field of the Invention
The present invention relates to an impact energy absorbing steering wheel comprising a ring portion, a spoke portion, a boss portion, and a pad containing an impact energy absorber. The upper side of the boss portion, and the upper surface of the pad are spaced from, but generally parallel with, the ring portion, with the pad being disposed so as to be between the ring and boss portions. The spoke core is made of material capable of plastic deformation such that when an impact force acts on the ring portion, the spoke core deformations causing the ring portion to reorient in the vertical direction.
2. Description of the Prior Art
FIG. 1 depicts a currently known steering wheel 11 having an impact energy absorber 6. This energy absorber 6 is generally constructed of sheet metal, having a U-shaped cross section, and is positioned on the upper side of a boss portion B. This energy absorber 6 includes a pad 5 with an upper surface 5a positioned such that the upper surface 5a is spaced apart from but parallel to the surface of the ring portion R, an impact energy absorber 6 of sheet metal having a U-shaped cross-section is contained on upper side of a boss portion B, and a pad 5 with an upper surface 5a nearly in parallel to the surface of the A self aligning mechanism 3 having an annular plate 3a and a plurality of deformable arm portions 3b is interposed between a boss 2 and a core 4 of a spoke portion S, with a pad 5 including an impact energy absorber 6 being fixed to the plate 3a of the self aligning mechanism 3. Further, the spoke core 4 is formed by steel capable of plastic deformation (refer to Japanese patent application laid-open No. 58-152660, utility model application laid-open No. 60-9764).
In such a steering wheel 1, if a generally horizontal impact force F is applied to the ring portion R, the deformable arm portion 3b of the self aligning mechanism 3 is deformed, causing the upper surface 5a of the pad 5 and the ring portion R to reorient so as to extend vertically, perpendicular to the acting direction of the impact force F (refer to FIG. 2).
If additional horizontal impact force F is applied, the spoke core 4 is subjected to plastic deformation and the ring portion R approaches the boss 2, as the ring approaches the boss portion, the ring portion becomes substantially coincidental with the pad 5 also coincides substantially with the ring portion R and the impact energy absorber 6 is subjected to plastic deformation causing the energy to be absorbed (refer to FIG. 3).
In such a steering wheel 1, the energy imparted by the impact force F is absorbed during the deformation of not only the deformable arm portion 3b of the self aligning mechanism 3, but also the deformations of the spoke core 4 and the impact energy absorber 6.